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Background: Changes in the biliary system after gastric bypass are not well defined. Dilation may be normal or due to biliary tract pathology, that latter of which is problematic to manage because access to the biliary tree following gastric bypass often requires specialized care due to altered anatomy. The purpose of this study is to review patients who underwent imaging of their biliary system both before and after Roux-en Y gastric bypass in an effort to elucidate the effect this operation has on hepatic duct diameter.

Methods: Using an IRB approved database, patients who underwent laparoscopic Roux-en Y gastric bypass from 6/1/2010 and 9/30/2011 were evaluated. Those with imaging both before and at least 3 months after gastric bypass were analyzed. Patients who underwent remote cholecystectomy prior to gastric bypass during this time period were included in subgroup analysis. Data collected included patient demographics, operative details, post-operative weight loss, and time interval between surgery and second imaging. Indications for post-operative imaging included abdominal symptoms. For purposes of this study, all imaging was re-reviewed by a radiologist whereby the common hepatic duct was measured at the level of the porta hepatis to determine interval changes.

Results: A total of 551 patients underwent Roux-en Y gastric bypass during the study period. Of these, 82 had biliary imaging both before and after surgery. Thirty-three patients had post-operative imaging at least 3 months following gastric bypass. Mean age was 44 years (21-65) and 79% were female. There were 8 patients who had remote cholecystectomy prior to gastric bypass and 25 patients with gallbladders. In all 33 patients, mean hepatic duct diameter was 5.2 +/- 2 mm and 7.1 +/- 2.6 mm pre-operatively and post-operatively respectively (p <0.01). Patients with prior cholecystectomy had hepatic duct diameters of 7.9 +/- 1.3 mm and 9.5 +/- 3.5 mm pre-operatively and post-operatively respectively (p=0.3). Patients who had not previously undergone cholecystectomy had hepatic duct diameters of 4.3 +/- 1.1 mm and 6.4 +/- 1.8 mm pre-operatively and post-operatively respectively (p<0.01). Overall excess weight loss was 26.8% at a mean follow-up of 8 months (3-14).

Conclusions: Hepatic duct diameter increases after Roux-en Y gastric bypass. Patients with prior cholecystectomy have a trend toward increased hepatic duct diameter, though this change was not statistically significant. A better understanding of this phenomenon may limit the need for further work-up in patients with incidentally detected biliary dilation and help to redefine what is considered normal and abnormal in this population.